Bobbin for dacron filaments



May 9, 1961 R. ATwooD Erm.

BoBBIN FOR DAcRoN FILAMENTS 3 Sheets-Sheet 2 Filed Aug. 5, 1954 INVETORS c. www y;

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May 9, 1961 R. ATwooD i-:rAL

BoBBIN FOR DAcRoN FILAMENTS 3 Sheets-Sheet 3 Filed Aug. 5, 1954 UnitedStates Patent BoBBrN Fon nAcRoN rrLAMENrs Rawson Atwood, Buttonwo'odLane,l Rumson, NJ., and Charles C. LAllemand, 168 The Fellsway, MurrayHill, NJ.

Filed Aug. s, 1954, ser. No. l447,942

1 claim. (cl. 24a-118.31)

' This invention relates to improvements in textile bobbins. l

More particularly, the invention is concerned with bobbins or tubes ofthe type used for winding filaments or fibers for shipment to the user,and with bobbins which may be subjected to relatively severe servicecondi- -tions.

The invention has for its general objects the production of abobbinmeeting a number of somewhat inconsistent Patented May 9, 1961bobbin is undesirable. For such reasons as these, the bobbin outerbarrel diameter is not a matter of free choice, but is confined withinrather narrow limits by the fiber manufacturers requirements.V

requirements, the principalones being: great strength combined withcheapness and lightness; a surface which, when cut or otherwise damaged,will 'not catch the yarn or fiber; and a high impact strength,particularly at the ends.

While the invention is not limited to such fields of use, its advantageswill appear mostV clearly with reference to the winding of modernsynthetics in low deniers, Daeron being a typical material illustratingvery fully severe requirements for a bobbin and the satisfying thereofby the structure and method of the'present invention. rIn the particularclass of service contemplated it has heretofore been found necessary toutilize laminated phenolic or other thermo-setting synthetic resins orplastics, and moreover, to utilize special preforms inthe molding, aswell as to perform accurate grinding and other finishing operations.Even so, the success of these expensive bobbin structures has been aqualified one.

It is ordinarily not permissible to select bobbin dimensions in arrivingat the best design, as lthe bobbin must be usable withexisting mandrels,chucks or spindles, and is sometimes limited also by the method ofwinding of the ber. For example, with lthe present commonly used methodand machinery Icertain critical or resonant diameters are encountered,at which, in view of the angle of wind, the fibers of successive 'layersmay lie close together in parallelism causing one fiber to catch anotherin unwinding, a condition known'V as ribboning, thus creating danger ofbreakage of the fiber and, in an extreme case, the loss of the entirepackage. Such critical diameters may exist, for example, at close to twoinches, four inches and eight inches, so that the package dimensions areconfined to inner and outer diameters of about two and four inches,respectively, four and eight'inches, respectively, etc. While thesmaller diameter package permits a bobbin of inherently greater strengthand lightness due to higher curvature, the quantity of fiber carried isonly about one` fourth as great, so that bobbin expense and weight mayactually be greater per pound of fiber than with a larger diameterbobbin. Also, the sharpness of bend of the fiber in being laid onto asmall diameter The fitting of existing mandrels requires a certainminimum inner bobbin diameter while the considerations above mentionedldictate the maximum outer diameter, with the result that the bobbinassumes the form of a rather large diameter thin-walled tube, whichnevertheless must have great strength together with a surface ofprescribed characteristics. The fulfilment of these requirements with abobbin of substantially homogenous construction has been found difiiculteven at great expense, and the construction of a composite bobbin alongknown or conventional lines has hitherto been found impractical for verysevere service conditions.

The bobbin of the present invention utilizes a steel, aluminum or otherbarrel member for obtaining the required' strength, which may beincreased by a forming operation such as beading, and obtains therequired surface characteristics and impact strength by molding ontooraround the steel 0r other shell a plastic cover extending beyond theends to take impact and prevent deformation by impact of the steel orother structural shell.

In the drawing- Fig. l is an isometric view of a bobbin embodyingtheinvention in a preferred form;

Fig. 2 is an axial section of the bobbin of Fig. l;

Fig. 3 is an enlarged section in an axialplan and showing the structureof one end of the bobbin barrel Wall;

Figs. 4 and 5 are views similar to Fig. 3, but on 'a smaller scale andshowing modifications; and

Fig. 6 is a central axial section, largely schematic, and showinggeneral arrangement of the mold, one end of which is shown in moredetail and to a larger scale in Fig. 3.

The bobbin comprises a supporting shell or structural barrel element 10,which may be formed of steel, aluminum alloy, or other comparably strongmaterial, and may further be formed or beaded as shown for increasingthe strength. Associated with the metallic shell 10 and preferablymolded in situ thereon as an insert is a plastic coverall. The presentlypreferred plastic material, all things considered, is thermo-plastic,modified polystyrene or styrene copolymer of the shock resistant or highimpact type being very' suitable. This material possesses v the desiredproperties as outlined below in a high degree,

but can, of course, be substituted by other covering materials whereverconditions permit or where somewhat different properties may be requiredfor the particular field of use. Nylon is suitable, but its use is notordinarily justified, in view of its much higher cost.

In general, a primary requirement for a bobbin surface is a certainsmoothness and softness, to prevent catching and breaking of thefilament. High impact polystyrene, in common with a good many` othermaterials possesses this property in a high degree. For example, the:customary method of removing unused material from a bobbin is to cutit'by a longitudinal knife stroke, which also tends to cut or furrow thebobbin surface. The plastic material referred to, when so cut, does notcut deeply, does not form shap burrs and may be burnished down withl anyround hardobject so as to present again a smooth surface which will notcatch the filament.v A

, 3 second requirement is suiicient strength to take the relatively highyarn pressures to which the material may be subjected. A thirdrequirement is impact strength and elasticity suicient to withstanddropping on to a concrete or other oor and also form a buier orprotection for the inner metal shell; the importance of this will appearmore fully in the following description. Economy is, of course, aconsideration and the material used is of relatively low cost in itselfand adapted to inexpensive manufacture, since it molds in a fastthermo-plastic cycle, with a good .surface finish and with a lowpercentage of rejects.

Referring now to Figs. 1, 2, 3, and 6 in some detail and moreparticularly to Figs. 3 and 6 which illustrate the method of formation,it will be observed that the bobbin may be molded in a thermo-plasticmolding press, typically of the injection type, utilizing a pair ofcavity dies 13 separating on an axial plane and a pair of cores 14 and15 movable axially toward and away from each other and -abutting along aline or plane 16 when in molding position. The mold may be gated at anyof a plural-l ity of convenient locations 17 for obtaining good flow ofplastic and distribution of pressure within the mold. Gating at fourpoints at the upper end of the mold (Fig. 6) has been found satisfactoryin bobbins of sizes and proportions such as worked with so far.

The inner metal shell is supported from the mold core at each end, asshown in Fig. 3. As there shown, the core is generally cylindrical orformed with such draft angle as may be required in any particular case.Toward the end of the shell 10, 4for example,`from the plane indicatedat 20 to the plane 21 nearer the end of the shell `10, the core istapered outwardly, and it is again tapered outwardly from plane 21 tothe plane 22 at the end of the shell 10. At this point a shoulder 23 isformed, and is followed by a section between planes 22 and 24 which isbeveled or tapered outwardly at a relatively sharp angle A, an angle ofabout 45, as shown, being suitable. Below plane 24 the core is againsubstantially cylindrical, having only such draft angle as may benecessary for removal from the mold, and the molding surface of the coreterminates in a rounded portion 25, cooperating with a similar roundedportion of the cavity mold parts 13, to form a rounded end on thebobbin.

For deniteness in description, the bobbin and its method of constructionwill be described with relation to specific dimensions of one actualsize of bobbin, and its characteristics will be related to a bobbin o-fthese ldimensions and size, it being understood, however, that theinvention is not limited to bobbins of this or any other particularsize, but is applicable quite generally to bobbins of a great variety ofdimensions and relative proportions.

In Fig. 3 of the drawing a variety of ldimensions are indicated, byreference characters B to I inclusive. The overall length, in theconstruction shown (dimension I) may be about 4 inches, and extensive ofthe classic covering.

' The length beyond the metal shell 10 (dimension H) may be aboutone-half inch or somewhat less, the length of the shell being thus about3 inches. 'I'he outside of the barrel in the construction shown is about4 inches and the inside diameter C about three and five-eighth inches,giving the overall wall thickness of about threesixteenths of an inch.The general extensional relationships may be obtained from the drawing,which is to scale, by knowing that the distance between planes and 21and between planes 21 and 22 is one-eighth of an inch. The `insidediameter of the metal barrel element 10, dimensionk B, is about- .005greater than the core diameter at that point. yThe taper between planes20 and 21 is relatively greatenbeing shown as .03 inch .increase indiameter, while the taperr between yplanes 21 and 22 may be very slightto only'a few thousandths increase in diameter to insure the rightthickness or may even be eliminated. 'Ihe increase in diameter betweenplanes 22 and 24 is not great, amounting again to about another .O3 inchand below this point the core is formed to only such slight draft angleas is necessary for molding purposes. The beaded metal shell 10 may beabout 18 gauge thickness, or about .O5 inch and varied in thicknessaccording to requirements. In view of the beading, the thickness of theplastic covering on the outside of the barrel may range 'from a maximumof about one-eighth inch, as at 32 to a of about onesixteenth inch orsomewhat less, as at 31, the minimum thickness in the construction shownbeing about .05 inch.

The tails 30 (Fig. l) left at the gating points are ground oit asdesired, and the entire barrel surface may be ground to eliminateany ashat the mold parting lines, this being a simple center grindingoperation.V

In the construction and method illustrated in Fig. 3, the metal barrel10 is selected with a length and inside diameter, so that it will tbetween the plane 22 and corresponding plane in the vother core member,and will be slightly expanded by the taper of the core, the precisedegree of expansion varying with variation in length and inside diameterof the membei-ltl within the permitted manufacturing tolerances. Ovalityof the barrel member is thus corrected, arcuate` centering with relationto the plastic cover is provided anda plastic-tight seal is provided toprevent plastic from entering the space between the member 10 and themold core elements.

Fig. 4 illustrates a modified form of moldandbobbin, which is identicalwith thatjust described except that the core elements are provided withgrooves such as the groove 39. vThree or four of thesegrooves,distributedv symmetrically around the axis ofv vthe core and bobbin maybe provided. These grooves'adrnit plastic into the interior of themember 10, covering fthe-inside and also providing internal bearingribs, 40, as vindicated. The ribs 40 may be removed, if desired.

Fig. 5 illustrates a further modification, in which a relatively thickmetal barrel member 10, which may advantageously be made of-laluminumIalloy is provided. Commercially available extruded or drawn tubing issuitable. The metal shell 10 may comprise half the total barrelthickness, the remainder being plastic. .Theouter surface of member 10'is smooth and cylindrical, and concentric with the core, the outermolded surface of the barrel and with the inner surface 42 of theplastic beyond the end of member 10'. The end of'barrel mem'ber 10 isformed to a radius as indicated at 41 so that the section of the plasticis gradually reduced between its thick end portion and its thin portionover the surface generally of the barrel 10. 'I'he relationship of theedge of the member 10 to the core is the same as in the embodimentpreviously disclosed with reference to Fig. 3.

As stated above', a very important requirement in bobbins of the typedisclosed is impact resistance, and it is found that a plastic coverextending beyond the end of the metal tube about three-eighths` of aninch or thereabouts provides an extremely satisfactory buffer or irnpactprotection for the metal barrel member. In both the form disclosed inFigs. 3 and 4 and that disclosed in Fig. 5, the4 conguration of the endof the metal barrel is such that the plastic thickness is reducedgradually, thus avoiding any undueV concentration of exing strain.

The length of the extension of the plastic beyond the ends of the metalbarrel member may be varied considerably, and in `general may conform toexisting practice in the winding of the lament, so that the part of thebarrel whichhas theber'or Vfilament wound upon it, is backed up by themetall barrel member, and the 5 ends of the barrel Where the plastic isnot thus supported is left bare.

What is claimed is:

A textile bobbin comprising a beaded tubular metal barrel member and aplastic covering therefor extending beyond the ends thereof, the metalbarrel member Aterminating at its ends at reduced diameter parts of thebeading so that the section of the plastic is gradually reduced from theextreme end of the metal barrel member by comparison with its sectionbeyond the end thereof, 10

the plastic covering conforming internally to the outer surface of themetal barrel member and being externally cylindrical.

References Cited in the le of this patent UNITED STATES PATENTS KuttnerMar. 17, 1914 Franklin Nov. 25, 1947 Wilson Aug. 31, 1948 Bates Nov. 16,1948 Broadbent et al. Nov. 17, 1953 Dunlap May 18, 1954 Klein July 24,1956 FOREIGN PATENTS Great Britain Oct. 14, 1953

